Kanye West’s collaboration with Paul McCartney on “All Day” was one of the most anticipated collaborations of 2015. Although McCartney is only explicitly in the song during his short addition to the bridge, it looks like we can credit McCartney for the melody of the entire song. Originally inspired by a Picasso painting in 1970, the melody comes from the Beatles’s unreleased track, “When the Wind Blows.” Years later, McCartney made an appearance on Parkinson, where he played the guitar and whistled the melody to what we now know as “All Day.” That’s right. Paul McCartney’s wrote his addition to “All Day” before Kanye West was even born. Stream “When the Wind Blows” and his stop by Parkinson below.